Entrance and propagation pattern of high‐frequency electrical currents in biological tissues as applied to fractional skin rejuvenation using penetrating electrodes

Abstract

Radiofrequency currents have a tendency to move toward the center of the bulk of tissue. When an electrode of a fractional radiofrequency device enters the skin, maximum heating effect will be around the tip of the electrode in the dermis. This phenomenon can preserve epidermis from injury during dermal heating, reducing post-procedural skin surface side effects seen with many skin rejuvenation procedures.

Successful Treatment of Refractory Melasma Using Invasive Micro-Pulsed Electric Signal Device

“…An experiment of non-insulated penetrating electrode placed in soft tissue of relatively uniform electrical impedance showed that under certain settings, thermal coagulation can be limited to the tip of the electrode and made to expand to the entire length of the needle by increasing energy. 17 It is known that radio frequency current from the needle electrodes placed in epidermis and dermis preferentially travels through tissues of higher electrical conductivity. Epidermis is known to exhibit greater electrical resistance.…”

Electromagnetic Initiation and Propagation of Bipolar Radiofrequency Tissue Reactions via Invasive Non-Insulated Microneedle Electrodes

“…Invasive RF systems, which deliver electromagnetic energy through electrodes that penetrate into target tissues, offer advantages of a deeper layer of treatment in a non-contiguous pattern, compared with noninvasive systems 4 5 6 7 . In a recent study, a monopolar 0.4-MHz RF system equipped with a single penetrating electrode induced thermal coagulation in ex vivo bovine liver tissue that started from the tips of non-insulated electrodes and formed a rim of coagulated tissue around the entire length of the needles with increasing energy levels 6 . Therein, the thickest rim of coagulated tissue was formed around the tips of the electrodes, suggesting that non-insulated penetrating electrodes can be used to effectively and safely deliver RF energy to the skin while preserving the epidermis 6 .…”

“…Meanwhile, research on invasive bipolar RF devices has suggested that electrodes must be insulated in order to preserve the epidermis 5 6 . In a predictive model, a minimally invasive bipolar RF system showed a thermal profile that was confined between the non-insulated portions of the penetrating electrodes 5 .…”

Improvement of Periorbital Wrinkles Treated with an Invasive Non-Insulated Microneedle Pulsed Electric Signal Device

“…5 As the microneedles are very thin and as the thermal coagulation can be limited to the tip of the electrode, dermal remodeling and rejuvenation can be gained more effectively avoiding unnecessary epidermal damage compared to noninvasive RF devices. [7][8][9][10] Effective RF energy delivery into the dermis by generating coagulation columns separately around each microneedle while preserving the epidermis has also been demonstrated by the invasive bipolar non-insulated microneedle RF device. 8 Microneedling can also induce elastin deposition together with neocollagenesis reversing solar elastosis caused by photodamage.…”

“…2,3,6 It has recently been shown that not only non-invasive RF systems but also invasive RF systems even with noninsulated electrodes can also safely deliver RF energy to the skin while preserving the epidermis. 7,8 In this report, we present three patients with different grades of periorbital wrinkles which were improved after treatment with a novel invasive pulsed electric signal device with noninsulated microneedle electrodes.…”